The field of the invention generally pertains to locks. The invention relates more particularly to a cap look assembly and system for deterring unauthorized access to a threaded cylindrical end of an access or security device, such as a Schrader valve.
An alarming trend in substance abuse has emerged where children inhale refrigerant gases, commonly sold under the trademark xe2x80x9cFreon,xe2x80x9d taken from air conditioning units. They do so to get a xe2x80x9chigh,xe2x80x9d only to become ill and ever die in extreme cases. Tapping into a freon line of an air conditioning unit is made simple and easy for children by the presence of Schrader valves used for servicing freon levels. By simply unscrewing a cap off the valve a child can operate the center pin to release freon gas. Such valve caps serve to cover and protect the center pin from damage, but do not prevent unauthorized access to the valve.
Various protective cap devices have been developed to deter similar unauthorized access by children to containers containing medicine and other potential poisons. Many of these child tamper resistant caps require only that the cap be depressed slightly while rotating the cap. Other similar caps have featured the use of a key to effect release, which in some cases have either complicated the key operation with a multitude of moving parts, or is arguably too simple and easily bypassed by children.
For example, in U.S. Pat. No. 3,426,932, a tamper-proof poison bottle closure is shown having an inner cap 14 capable of threadedly securing to a threaded neck 10 of a bottle and enclosed by an outer cap 32. A torque may be exerted on the inner cap for opening and closing, by using a key 43 to turn a threaded disk-like collar 52 positioned within the outer cap and above the inner cap. Rotation of the collar produces rack-and-pinion actuation of a pair of block-like slides 60 slidably held on vertical tracks 62 along the inner surface of the outer cap. In this manner, and as shown in FIG. 2 of the ""932 patent, the block-like slides engage a rib 40 along the top of the inner cap to unscrew the inner cap upon rotation of the outer cap. While this prior art bottle closure serves to restrict access, the many moving components of its rack-and-pinion mechanism may be overly complicated and economically burdensome for mass production.
Additionally, in U.S. Pat. No. 6,032,811, another child-proof cap assembly is shown having an inner cap 11 and enclosed by an outer cap 3. Both the outer cap and inner cap each have respective key slots 6 and 14 which are adapted to receive a key 7. Additionally, the inner cap has an alignment mark 15, and the outer cap has an alignment aperture 16 for assisting a user in aligning the key slots. Upon successful alignment, the key may be inserted through the slots and subsequently rotated to unscrew the inner cap from the container. One of the disadvantages of this prior art cap is that the key itself is attached to and kept together with the cap. Moreover, the slot engagement and operation of the inner cap may be easily manipulated with readily available tools, such as a screwdriver.
And finally, in U.S. Pat. No. 738,917, a bottle stopper is shown having a threaded inner shell for threadedly engaging a neck portion of a bottle, and an outer capsule which encloses the inner shell. The inner shell has a pair of studs 16, 17 extending above a transverse cap portion 4 of the inner shell. A key D have a pair of radial webs 24 is inserted though a key-receiving perforation 11 and engaged with the studs to directly exert a torque on the studs. Arguably, operation of this prior art cap lock is simple, straightforward and intuitive, presenting little difficulty for children having access to the key.
In summary, it would be advantageous to provide a zap lock for deterring children from accessing a restricted space or location and operable by means of a key. Moreover, while the cap lock should be simple in structure, it would be beneficial for the key operation of the cap lock to be sufficiently non-intuitive such that obtaining the key does not guarantee access to the cap lock.
An unrelated problem has arisen from the use of a single size of Schrader valve for feeding different refrigerants, such as those sold under the trademarks xe2x80x9cFreon R22,xe2x80x9d xe2x80x9cFreon R410,xe2x80x9d and xe2x80x9cFreon R12.xe2x80x9d These different refrigerant gases are not compatable. A careless service person could easily feed the wrong refrigerant gas into the Schrader valve, since all systems use the same valve. It would thus, be useful to provide a key which wil only open a lock for one composition of refrigerant gas to help eliminate this potential mistake,
It is thus a general object of the present invention to provide a cap lock assembly and system for restricting access to a threaded cylindrical end of an access or security device, such as a Schrader valve.
It is another object to provide a lock for a Schrader valve a which will open only if the correct key for a specific refrigerant gas is inserted in the lock.
It is a further object of the present invention to provide a cap lock assembly and system having a swivel connection between an inner lock and an outer cap, which prevents release of the inner lock without a key.
It is a still further object of the present invention to provide a cap lock assembly and system which utilizes an abutment tab of a key to pivotally abut the inner lock against the outer cap, to simultaneously (1) produce a transverse wedging force between the inner lock and the outer cap, and (2) transfer a torque on the transversely wedged inner lock.
It is a still further object of the present invention to provide a cap lock assembly and system which provides journal-bearing support to a pivot axis of a key.
It is a still further object of the present invention to provide a cap lock assembly and system whose locking and unlocking mechanism is not readily apparent, even after viewing through a keyhole.
It is a still further object of the present invention to provide a cap lock assembly and system utilizing a key having a faux pivot shaft which is offset from a perceived pivot axis.
It is a still further object of the present invention to provide a simple and cost-effective cap lock assembly and system utilizing a minimum number of parts to effect the foregoing objects, and which is easily machined and manufactured by conventional machining and manufacturing methods.
The present invention is for a cap lock assembly and system for use with a threaded cylindrical end of an access or security device, such as a Schrader valve. In a preferred embodiment, the cap lock system comprises an outer cap having an upper endwall and a cylindrical cap sidewall which extends down from the upper endwall to an open lower end. And the open lower end leads into a cap cavity defined by the outer cap sidewall. The upper endwall has a keyhole extending through the endwall with a journal-bearing section which defines a key pivot axis and supports radial loads.
Additionally, the system comprises an inner lock which is telescopically and captively received within the cap cavity of the outer cap. A radial clearance is provided between the inner lock and the outer cap to enable free rotation about a central axis of rotation and thus prevent the inner lock from being unscrewed. The inner lock has a cylindrical lock sidewall extending between a top end and an open bottom end, with the top end having an annular flange surrounding a recessed cavity which is in communication with the keyhole. The open bottom end leads into an internally-threaded cavity defined by the lock sidewall. The internally-threaded cavity is configured to threadedly receive the threaded cylindrical end of the access or security device when it is rotated about the central axis of rotation.
And finally, the system includes a key used for locking and unlocking the outer cap and inner lock combination. The key has a pivot shaft extending to a leading end, a tab radially connected to the pivot shaft at the leading end, and a key handle for applying a torque on the pivot shaft. The pivot shaft is configured to be matingly inserted into the journal-bearing section of the keyhole and to pivot about the key pivot axis. And the tab is configured to be inserted through the keyhole into the recessed cavity and to pivotally exert a transverse force against the annular flange when a torque is applied on the pivot shaft. When operated in this manner, the inner lock is offset with respect to the outer cap and wedged against the outer cap. The wedging action allows the torque from the key to be transferred to the inner lock so as to effect screwing on or off the threaded cylindrical end.